Process of manufacturing rubberized cords



Aug. 9, 1-932. E. HOPKINSON 1,871,412 7 v PROCESS OF MANUFACTURING RUBBERIZED CORDS Filed-June 19. 1929 INVENTOR Erncsif $021 l i TORNEY Patented .Aug. 9, 1932 UNITED STATES PATENT OFFICE.

PROCESS OF MANUFACTURING RUBBERIZED CORDS Application filed June 19,

This invention relates to a process for treating cords or yarns such as are used in the manufacture of pneumatic tires.

Heretofore it has been the practice to manjfl ufacture cords or yarns for use in the manufacture of tires with j a desired tensile strength and stretch, an increase in stretch being obtained by increasing the number of twists per unit of length.

The present invention aims to produce cords for tire fabric with a high stretch without the necessity of increasing the number of turns per unit of length in the twisting operation and Without diminishing the tensile strength which results therefrom.

With a preferred embodiment in mind but without intention to limit more than is required by the prior art, the invention consists in subjecting cords of any given manufacture to shrinkage by passage through a bath of hot water, maintaining the cords in substantially this shrunk or contracted condition, and rubberizing the cords in any suitable and convenient manner.

In the drawing, one of the many possible embodiments of the invention is illustrated diagrammatically. Referring to the drawmg:

1 indicates a creel (diagrammatically) from which a series of cords 2 are drawn off through a pair of lease rods 3 and a comb 4 by means of a pair of rolls 5, preferably faced with vulcanized rubber to insure against slippage. The cords 2 pass from the rolls 5 to a bath 6 of a shrinking medium, such for instance as water at a temperature preferably of approximately 200 F. which immediately causes the cords to shrink and increases the number of twists per inch of length. The cords pass beneath the roll 8 in the bath and out through a pair of rolls 7 which preferably have a surface speed about 5% slower than the rolls 5. The relative speed of the surfaces of the two pairs of rolls 5 and 7 may be varied as desired to maintain the cord in shrunk condition. In-

stead of water alone at an elevated temperature, materials such as caustic soda or other material may be added to the water to increase the amount of shrinkage where such 1929. Serial No. 371,989.

medium which has been squeezed therefrom by the rolls 7, around a roll 9 and beneath roll 10 immersed in a bath of artificial or natural rubber latex 11.

From the latex bath 11 the cords may be conducted through an adjustable comb 12 between a pair of doctor blades 13 for removing any excess latex, and over rolls 14 and around guide roll 15 to a series of dry cans 16 which may be heated in'any suitable and convenient manner, a fabric liner 17 being drawn from a spool 18 so as to be interposed between the first dry can and the 1atex treated cords. The liner 17 also takes the strain off the latex treated cords as the water is being removed from the. latex and thereby the shrinkage which has been obtainedby the shrinkingtreatment at station 6 is retained in the rubberized weftless fabric which is ultimately drawn off from the dry cans around the roll 20 and accumulated on a spool indicated at 21, the liner being separated at the roll 20 and wound up on the spool 19. p

The rolls 7, 9, 10, 14, 15 and 20 and the dry cans 16 are all positively driven in such manner as toinsure the movement of cords through the apparatus without any substantial tension and without any substantial loss of the shrinkage obtained by the initial hot water or equivalent treatment.

Obviously the invention may be variously practiced and is not limited in its broadest aspects to the specific procedure above de-. tailed. For instance the hot water or equiv- .alentshrinkage treatment may be performed at the cotton mills and the dried cords in spools or on warp beams deliveredto the factories for rubberization either by treat ment with rubber latex. or equivalent aqueous dispersions of rubber or by passage through a calendar for applying sheets of rubber composition to one or both sides of a layer of close lying parallel cords. In other words, any way of applying rubber composition, either in aqueous dispersion or in a dry condition may be employed in connection with this invention whose broad underlying principle comprehends an initial shrinkage treatment with a liquid shrinking medium.

Of course the invention comprehends a plurality of immersions in a shrinking medium with or withoutany intermediate dryings or partial dryings, and also the treatment of individual or separate cords alone or simultaneously or of a cord fabric (having widely spaced and weak filling threads) and is not limited merely to the formation of a weftless fabric, assuch alternatives are obvious and may be adopted by manufacturers to meet specific requirements. While the rubber composition may be applied variously, as above indicated, it is preferred to apply it partially or wholly in the form of a natural or artificial aqueous dispersion of rubber.

However, the rubber in the aqueous dispersion whether a natural rubber latex or an artificially prepared aqueous dispersion, may be vulcanized or the dispersion may contain vulcanizing ingredients capable of complete vulcanization of the rubber particles after the water of the dispersion has been evaporated.

The value of the invention was determined by comparative tests of cords of 21.35/5/3 K. P. (carded peeler) construction. In one case two duplicate specimens of weftless cord fabric were prepared, the cords being held together by a thin coating of rubber ob tained after drying applied rubber latex. One duplicate specimen so constructed was immersed in hot water at a temperature of 95 C. before being passed through a bath of rubber latex, and the other duplicate specimen was treated directly with the rubber latex composition without such hot water treatment.

The strength of one 15-end specimen strip not subjected to a shrinking treatment was 273.7 lbs. whereas the same strip subjected to a hot water shrinking treatment possessed a strength of 267.8 lbs, the drop in strength amounting to approximately 2.16%. The stretch of the same 15-end specimen at break non-shrunk is 19.59%, whereas the corresponding specimen shrunk according to the present invention has a stretch at break of 25.6%, thus showing a gain of approximately Corresponding comparative tests were made of a single cord of the above identified out shrinking. Tests of the tensile strength and of the stretch at break of such single cords were made. The single cord had a strength of 19.61 lbs. without shrinking whereas with shrinking it had a strength of 19.28 lbs., there being an inconsequential loss of its fibrous constituents, a substantial increase in stretch which is, of course, achieved vat much less expense than if it was attempted by twisting. Moreover, this increase in stretch is obtained with an inconsequential sacrifice of strength, at least as compared with other methods of obtaining an increased stretch, such as what is generally known in the trade as a high stretch and low twist or the so-called high stretch obtained by means of a high twist.

Cords or cord fabric (with or without a weak filling thread at greater intervals than the warp elements) made according to the present invention may be advantageously em ployed in the manufacture of a wide variety of rubber articles but the invention is especially directed to the manufacture of such material for incorporation in tire casings.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. That method of treating separate twisted cords which consists in subjecting them to the shrinking action of water, maintaining the same in their shrunk condition, and subsequently applying rubber-containing-material thereto while in shrunk condition.

2. That method of treating separate twisted cords which consists in subjecting a plurality of cords to a liquid at a temperature of approximately 200 F. thereby decreasing their unit length, and treating the cords while decreased in length with rubber-containing-material.

3. That method of treating separate twisted'cords which consists in continuously, advancing a multiplicity of cords, through a waterbath' at a temperature substantially above room temperature and shrinking the cords, and subsequently while the cords are shrunk and maintained in parallel and substantially contiguous relation applying rubber-containing-material to form a rubberized weftless fabric.

4. That method of *treating separate twisted cords which consists in successively and continuously advancing a plurality of cords through a bath of shrinking medium and at a lesser linear speed through a bath of an aqueous dispersion of rubber, and drying the treated cords.

5. That method of treatmg separate twisted cords which consists in conducting a plurality of cords through a hot liquid capable of shrinking them, withdrawing the cords from the liquid at a speed compensating for the shrinkage thereof, and applying rubbercontaining-material to the cords while advancing them at a speed substantially equal to their speed of withdrawal from the hot liquid.

6. That method of treating separate twisted cords which consists in conducting a plurality of cords successively through baths of a shrinking medium at approximately 200 F. and of an aqueous dispersion of rubber and without substantially tensioning the cords intermediate the baths, and drying the cords so as to form a weftless fabric therefrom. a v

7. That method of treating separate twisted cords which consists in conducting the cords through a heated liquid capable of shrinking them and at a predetermined speed withdrawing the cords from the heated liquid at a speed approximately five percent (5%) slower than the speed of their advance into the heated liquid, treating the cords with an aqueous dispersion of rubber, and drying them in contiguous parallel relation so as to form a rubberized weftless fabric thereof.

8. That method of treating separate twisted cords which consists in passing twisted cotton fibres constituting cords or cord elements through a hot aqueous shrinking medium and increasing the twists per unit length, withdrawing the same from said medium at a rate of speed compensating for the shrinkage in length and introducing said cord or cord elements into an aqueous dlspers1on of rubber-oontalmng-material, withcord elements from drawing said cords or said dispersion, and

g. Signed at New York, N. Y., this 17th day of June, 1929.

- ERNEST HOPKINSON. 

